By Linda Conlin, Pro to Pro Managing Editor

Current estimates are that presbyopia affects approximately 1.8 billion people around the world, and as the world population ages (we’re living longer), that number will rise considerably. Contemporary presbyopia correction with contact lenses includes monovision and multifocal lenses. But what if a contact lens could transition from distance to near vision as seamlessly as our younger eyes? Based on the volume of new patent filings and prototypes, accommodating contact lenses are in our future.

According to a paper recently published in Contact Lens and Anterior Eye, there are two hurdles to overcome for an accommodative contact lens. First, the user’s gaze must be tracked for changes in viewing distance, and second is control of the focal length. Approximately 2.00 diopters of additional plus power is needed for near vision. That sounds like a tall order, but innovative solutions are in the works.

One method involves a fluid-filled contact lens. Most near gaze is downward, and the lens works on that principle. When the wearer looks down, the lower lid presses on the lens. That pressure causes fluid in the lower part of the lens to move upward, increasing plus power for near vision. Upon distance gaze straight ahead, the fluid returns to the lower part of the lens and the distance power is restored. An electromechanical pump embedded in the lens to move fluid to change the lens shape and power is also under consideration. Another method similarly uses gaze position to change power. When the lower lid presses on the lens for near gaze, the lens lifts from the cornea and changes shape. More tear film gets behind the lens, and the combination of shape change and increase in the lacrimal lens adds plus power.   

What about gaze tracking? For that, we need a different type of lens. Microelectronic sensors embedded in the lens track changes in gaze based on changes in an electrical charge. The changes control the lens optics. Transmission of gaze information to an external device can also control lens power. Like other “smart” contact lenses, these lenses require a power source and an antenna. Contact lenses using liquid crystal displays (LCDs) are in the pipeline, too. Liquid crystals form parallel rods in their natural state. Reorienting the rods with a low voltage electrical charge changes the refractive index of the lens, and so the power.

Patents and patent applications have been filed for these designs, and clinical trials have been proposed, while some already are under way. It will take much more time and trial before lenses like these are available, but as the technology for contact lens materials and microelectronics progresses, they are on a bright horizon.

Learn more about contact lenses of the future with our CE, Therapeutic Contact Lenses and beyond at